PCI: Enable Configuration RRS SV early

Following a reset, a Function may respond to Config Requests with Request
Retry Status (RRS) Completion Status to indicate that it is temporarily
unable to process the Request, but will be able to process the Request in
the future (PCIe r6.0, sec 2.3.1).

If the Configuration RRS Software Visibility feature is enabled and a Root
Complex receives RRS for a config read of the Vendor ID, the Root Complex
completes the Request to the host by returning PCI_VENDOR_ID_PCI_SIG,
0x0001 (sec 2.3.2).

The Config RRS SV feature applies only to Root Ports and is not directly
related to pci_scan_bridge_extend().  Move the RRS SV enable to
set_pcie_port_type() where we handle other PCIe-specific configuration.

Link: https://lore.kernel.org/r/20250303210217.199504-1-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

@@ -1373,8 +1373,6 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL,
 			      bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT);
 
-	pci_enable_rrs_sv(dev);
-
 	if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
 	    !is_cardbus && !broken) {
 		unsigned int cmax, buses;
@@ -1615,6 +1613,11 @@ void set_pcie_port_type(struct pci_dev *pdev)
 	pdev->pcie_cap = pos;
 	pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
 	pdev->pcie_flags_reg = reg16;
+
+	type = pci_pcie_type(pdev);
+	if (type == PCI_EXP_TYPE_ROOT_PORT)
+		pci_enable_rrs_sv(pdev);
+
 	pci_read_config_dword(pdev, pos + PCI_EXP_DEVCAP, &pdev->devcap);
 	pdev->pcie_mpss = FIELD_GET(PCI_EXP_DEVCAP_PAYLOAD, pdev->devcap);
 
@@ -1631,7 +1634,6 @@ void set_pcie_port_type(struct pci_dev *pdev)
 	 * correctly so detect impossible configurations here and correct
 	 * the port type accordingly.
 	 */
-	type = pci_pcie_type(pdev);
 	if (type == PCI_EXP_TYPE_DOWNSTREAM) {
 		/*
 		 * If pdev claims to be downstream port but the parent